Process for making piece-dyeable frieze carpets from heat-set multicomponent acrylic fiber yarn



United States Patent 0 3,429 017 PROCESS FOR MAKING PIECE-DYEABLE FRIEZECARPETS FROM HEAT-SET MULTICOMPONENT ACRYLIC FIBER YARN Winfried T.Holfeld, Holiday Hills, Wilmington, Del., assignor to E. I. du Pont deNemours and Company, Wilmington, Del., a corporation of Delaware NoDrawing. Filed Oct. 14, 1964, Ser. No. 403,901 U.S. Cl. 28-72 7 ClaimsInt. Cl. D06c 1/08, 7/00 ABSTRACT OF THE DISCLOSURE A process comprisingbulking a skein of yarn of multicomponent acrylic fibers free fromapplied tension by subjecting the skein to elevated temperature andsteam, drying the bulk yarn under relaxed conditions, heatsetting theyarn by subjecting it to steam above atmospheric pressure and thendrying the heat-set yarn under relaxed conditions. This controlledprocess sequence provides yarns which are highly suited for makingfrieze carpets which can be piece dyed without loss of frieze twist inthe yarns.

This invention is concerned with frieze carpets. It is particularlyconcerned with a process for making piecedyeable frieze carpets fromacrylic fibers.

It is well known that polyacrylonitrile and copolymers containing amajor portion of acrylonitrile have poorly defined crystalline structureas compared to polyamide and polyester fibers. [It has not been possibleto heat set the acrylic fibers as successfully as has been done withpolyamide and polyester fibers. Thus the latter fibers, afterheat-setting, can be boiled in water without losing their heat-setshape. But the hot-wet modulus of acrylic fibers is so low that anacrylic fiber usually forgets all its past history when it is boiledoff. For this reason it has been considered impossible to piecedyecertain fabric structures made from acrylic fibers.

Frieze carpets are made from highly twisted pile yarns and after weavingor tufting the yarn loops are cut. To make a satisfactory frieze carpetit is essential that the cut yarns maintain their tightly twisted stateso that each tuft of yarn remains as a distinct entity. If he friezecarpet is dyed or boiled off after weaving or tufting, and after theloops are out, there is tendency for the yarns to untwist and lose theirindividuality, resulting in a mass of evenly distributed pile fibers.For this reason it has heretofore been considered impossible to piecedye frieze carpets made from acrylic fibers. Such carpets have been madeby stock dyeing the fibers before spinning into yarn. Yarn dyeing can bedone under carefully controlled conditions but is not attractiveeconomically.

The present invention provides a process of making frieze carpets fromacrylic fibers which carpets can be piece dyed without loss of friezetwist in the yarns.

This is accomplished by a process involving a carefully controlledsequence of bulking and texturing, relaxed drying, heat-setting, andfurther relaxed drying of yarn, followed by preparation of the fabricand dyeing it. The heat-setting of fibers is a well known art and iscommon practice with polyamide and polyester fibers, but is of onlylimited use with fibers of acrylonitrile 3,429,017 Patented Feb. 25,1969 polymers. :It is, therefore, surprising that a process has beendiscovered whereby piece-dyeable frieze carpets can be made fromacrylonitrile polymer fibers.

Piece dyeability is an important factor in the economics of textilemanufacture. Since dyeing is nearly the end of the production cycle, theproblem of inventory is much simpler if only undyed fabric needs to bestocked so that orders can be filled quickly for any shade desired.Without piece dyeability there must be carried a large inventory of dyedstaple or yarn, or a large inventory of carpets in all shades, to permitquick delivery. Piece dyeing is economical in other ways also and thebroad advantages of piece-dyeability will be obvious to those skilled inthe art of textile manufacture.

The fibers which are suitable for this invention are the multicomponentfibers, particularly bicomponent fibers spun from two different polymersor copolymers in a side-by-side relation along the length of the fiberas taught by U.S. Patent 3,038,236 of Breen. Certain blends of thesebicomponent fibers with homofibers are also satisfactory as will beshown in the example. A fiber blend may also contain fibers spun fromincompletely mixed solutions of different polymers according to BritishPatent 760,179 to Halbig.

The following example will demonstrate the manner in which thisinvention is carried out.

Example I A frieze carpet is made from yarn spun from a blend of abicomponent fiber and a homofiber. The two fibers have the followingpolymer compositions:

Fiber I--Bicomponent fiber: Percent Polymer A-Polyacrylonitrile 50Polymer B96% acrylonitrile, 4% sodium styrenesulfonate 50 FiberIIHomofiber: Percent Acrylonitrile 93.6 Methyl acrylate 6.0 Sodiumstyrenesulfonate 0.4

Fiber I is a 12 denier (1.33 tex) fiber spun according to Example VI ofU.S. Patent 3,038,236. After spinning it is washed and drawn 265% (3.65cut into 3inch (7.62 cm.) staple and dried.

Fiber II is a 17 denier (1.89 tex) fiber. After washing, it is stretched112% (2.12 x), cut into 3-inch (7.62 cm.) staple and dried.

Fibers I and H are blended in a 50/50 ratio and spun on the wollensystem into 1.25 Wool Run (248 tex) yarn having 3.5 turns per inch(t.p.i.) (1.38 turns per cm.) Z twist. Two of these yarns are plied andtwisted 8 t.p.i. (3.1 t.p. cm.) S twist.

The yarn is next wound into 54-inch (137 cm.) skeins of 1 pound (0.45kilogram) each and laced loosely to allow for bulking. The skeins arethen treated as follows to develop frieze texture and bulk:

(1) Steam 30 seconds in a slow-speed tumbler (such as a commercialwashing machine).

(2) Flex (work) the steamed skeins to develop texture and bulk.

(3) Steam 30 seconds.

(4) Flex.

(5) Steam 30 seconds.

(6) Dry in a relaxed state at 77 C. as by low speed tumbling or by traydrying. Drying at this stage can be omitted if the yarns are handledcarefully to transport them to the heat setting equipment. However, itis usually considered good practice to dry before proceeding to heatsetting. If the skeins are dried in a hanging position the crimp ispartly removed and the final carpets are not piece-dyeable.

(7) Heat-set in an autoclave by the following steps:

(a) Vacuum at 26 to 28 inches (66 to 71 cm.) of

mercury min 4 (b) Steam 10 p.s.i.g. (0.7 kilogram per square Cm.) min 4(c) Lag, reduce to 2 p.s.i.g. (0.14 k./sq. cm.) sec 20 (d) Steam lp.s.i.g. (0.7 k./sq. cm.) min 4 (e) Lag, reduce to 2 p.s.i.g. (0.14k./sq. cm.) sec 20 (f) Steam 10 p.s.ig. (0.7 k./sq. cm.) min 4 (g) Lag,reduce to 2 p.s.i.g. (0.14 k./sq. cm.) sec 20 (h) Steam 10 p.s.i.g. (0.7k./sq. cm.) min 8 (i) Vacuum 26-28 inches (6671 cm.) of mercury min 4(j) Exhaust to atmosphere sec 30 (8) Dry relaxed by tumbling or on trayat 77 C.

Following heat-setting and relaxed drying the yarns are made intocarpets by tufting on a 40-inch (102 cm.) tufting machine to 26 to 28oz./sq. yd. (871 to 938 gm./sq. meter), 0.375 inch (0.95 cm.) pileheight and 0.187 inch (0.47 cm.) gauge. The loops are cut after tufting.The individual yarns retain twist and identity.

The tufted carpet is 30 inches (76 cm.) wide. A 36 yard (32.8 meter)length is dyed in a 4 foot (1.2 meter) wide dye-beck by the followingschedule:

(A) Scour 30 minutes at 50 C. with 0.5 g./l. nonionic detergent.

(B) Add: 1.5% non-ionic detergent and 10.0% glaubers salt (based onweight of carpet).

(C) Run 5 minutes.

(D) Adjust pH to 4.5-5.0 with acetic acid.

(E) Adjust reel speed to 40 yards (36.4 meters) per minute.

(F) Add:

0.030% Sevron Blue BGL (Color index Basic Blue 35),

0.032% Sevron Blue B (Color index Basic Blue 21),

0.058% Sevron Red GL (Color index Basic Red 18), and

0.040% Sevron Yellow MF (Color index Basic Yellow (G) Raise temperatureto 71 C., run 30 minutes.

(H) Add 1.5% aromatic dispersing agent, run 5 minutes.

(I) Raise temperature to 88 C. during 20 minutes.

(I) Raise tempearture to 94 C. during minutes.

(K) Run 30 minutes at 94 C.

(L) Raise temperature to 98 C. during 5 minutes.

(M) Cool slowly to 77 C., rinse slowly with fresh water.

(N) Remove from beck and pass over vacuum slot.

(0) Dry on pin tenter at 121 C.

(P) Latex back of carpet and cure at 121 C.

This carpet retains its frieze pattern with each yarn tuft remainingtightly twisted. This result is similar, in clarity of frieze pattern,to a carpet tufted from yarns spun from stock dyed fiber. It is greatlysuperior in tuft clarity to a similar carpet made from yarns, which atsteps 6 and 8 above, were dried by hanging and blowing with hot air. Inthe latter case the tufts untwisted to a large extent yielding mostly asmooth pile carpet.

Other means of drying the yarns may be used in steps 6 and 8 of thebulking and heat setting operations but the yarns must be relaxed.Tumble drying is preferred because it gives good results and iseconomical and convenient. Drying can be done in bags, if desired, andwill \help prevent yarn entanglement. Yarns may also be dried on trays.

Efforts to produce piece dyeable frieze carpets of acrylic fibers byother methods of bulking and heat-setting the yarns have beenunsuccessful.

The temperature of drying the yarns in steps 6 and 8 is not critical andmay vary from room temperature (20 C.) to 130 C. or higher.

Example II A frieze carpet yarn is made from a bicomponent fiber spunfrom two different polymer compositions as follows: Composition I: PartsPolyacrylonitrile 84.0

Terpolymer of acrylonitrile, 93.6%; methyl acrylate, 6.0% sodiumstyrenesulfonate, 0.4% 9

Tris(dibromopropyl)phosphate (TBP) 7.0 Composition II:

Terpolymer of acrylonitrile, 93.6%; methyl 'acrylate, 6.0%; sodiumstyrenesulfonate, 0.4% 93.0

Tris(dibromopropyl)phosphate 7.0

The bicomponent fiber is spun in the same way as the bicomponent fiberof Example I. After spinning the fiber is washed and drawn 3X, thencrimped in a stulfer box crimper to impart from 6 to 8 crimps per inch.It is cut into 3-inch (7.6 'cm.) staple and dried at 130 C.

The staple fiber is spun on the woolen system to 2.4 cotton count (250tex) 4 turns per inch (1.6 turns per cm.) Z twist. Two of these yarnsare plied and twisted 8 t.p.i. (3.2 t.p. cm.) S twist.

The two-ply yarns are bulked and heat set as in Example I and tuftedinto a carpet with cut loops. When piece dyed as in Example I the yarnsretain their curled structure to yield a good frieze appearance.

Another useful fiber blend for use in practicing the invention iscomposed of composite fiber one side of which 15 formed of a mixture ofparts of polyacrylonitrile and 10 parts of a copolyrner (a) of 95.8parts of acrylonitrile and 4.2 parts of sodium styrenesulfonate and theother side of which is the copolymer (a) just given, and homofibercomposed of a terpolymer of acrylonitrile. Another useful fiber blend iscomposed of a composite fiber hav- 1ng the composition of thebicomponent fiber of Example II, and homofiber comprising Composition IIof Example II, that is a mixture of the terpolymer and phosphate asgiven therein. All parts stated in this specification are by weight.

The polymers of acrylonitrile useful in practicing the present inventionare well known. Generally these comprise homopolymers of acrylonitrileor copolymers of acrylonitrile and one or more ethylenically unsaturatedmonomers which are copolymeriz-able with acrylonitrile. Examples oftypical copolymerizable monomers are Well known and may be found in US.Patents 2,837,501, 2,485,241 and 2,436,926. The polymers generally havea molecular weight of about 15,000 to 250,000, and comprise at least 70weight percent of acrylonitrile. In addition, it should be apparent thatconventional additives may be incorporated in the polymers in the usualamounts without departing from the scope of this invention. The polymersare spun to bicomponent or other form useful for the invention inaccordance with teclmiques known in the patent literature for example asin US. Patent 3,038,- 236 and similar patents.

In choosing polymers for use as the different components of the fibersand yarns in the invention, due consideration must be given to therequired difference in shrinkage so that bulking will occur upon heatrelaxing. Similarly, fiber denier characteristic of carpet manufactureis to be employed.

While the invention has been described with detailed embodiments, itwill be appreciated that changes can be made without departing from itsscope. By Way of example, it will be apparent that changes andmodifications can be made in the detailed heat-setting and dyeingprocedures. Other changes will occur to those skilled in the art.

What is claimed is:

1. In the process of making piece-dyeable frieze carpet from yarnComprising composite acrylic fibers, the steps comprising forming askein of the yarn, subjecting the skein of yarn free from appliedtension to elevated temperature and steam to bulk the yarn, drying thebulked and relaxed yarn, heating the yarn with steam above atmosphericpressure to set it, and then drying the heat-set yarn free from appliedtension.

2. A process according to claim 1 in which the acrylic fibers comprise ablend of (1) homofiber composed of a terpolymer of acrylonitrile and (2)composite fiber one side of which is composed of polyacrylonitrile andthe other side of which is a copolymer of acrylonitrile and sodiumstyrenesulfonate.

3. A process according to claim 2 in which the yarn is heat relaxed at atemperature of about 77 C.

4. A process according to claim 1 in which the acrylic fibers comprisebicomponent fibers the components of which have difierent shrinkagecharacteristics.

5. A process according to claim 1 in which the acrylic fibers comprise ablend of (1) composite fiber one side of which is a mixture of 90 partsby weight of polyacrylonitrile and parts by weight of a copolymer of95.8 parts of acrylonitrile and 4.2 parts of sodium styrenesulfonate,and the other side of which is composed of copolymer of 95.8 parts ofacrylonitrile and 4.2 parts of sodium styrenesulfonate, and (2)homofibers composed of a terpolymer of acrylonitrile.

6. In the process of making piece-dyeable frieze carpet from yarncomprising a blend of (1) composite fiber one side of which ispolyacrylonitrile and the other side of which is a terpolymer ofacrylonitrile, methyl acrylate and sodium styrenesulfonate, and (2)homofiber composed of terpolymer of acrylonitrile, methyl acrylate andsodium styrenesulfonate, the steps comprising forming a skein of theyarn, subjecting the skein of yarn free from applied tension to elevatedtemperature and steam to bulk the yarn, drying the bulked and relaxedyarn, heating the yarn with steam above atmospheric pressure to set it,and then drying the heat-set yarn free from applied tension.

7. A process according to claim 6 in which the composite fibers areformed on one side of a mixture of 84 parts, by weight, ofpolyacrylonitrile, 9 parts by weight of a terpolymer of 93.6- parts ofacrylonitrile, 6 parts of methyl acrylate and 0.4 part of sodiumstyrenesulfonate, and 7 parts by weight of tris(dibromopropyl)phosphate, and on the other side a :mixture of 93 parts of a terpolymerof 93.6 parts of acrylonitrile, 6 parts of methyl acrylate and 0.4 partof sodium styrenesulfonate, and 7 parts of tris(dibromopropyl)phosphate.

References Cited UNITED STATES PATENTS 6/1962 Breen. 11/1963 Fujita etal 8130.1

